Once again, I'd like to point the interested reader to my own take on the issue of interlanguage links: http://brightbyte.de/page/Ideas_for_a_smarter_inter-language_link_system.
I still believe that that would be better than a central place for managing interwikis. In a nutshell: edit locally, like now, but compare globally, and show also *incoming* interwiki links.
-- daniel